I've seen a lot of cards using watercolour wash backgrounds but I am particularly indebted to Natalie Lappako, aka the Stamp Witch, who recently did a lovely card using watercolour wash and Beachy Little Christmas and so I guess I've cased her! Check out her blog as it is wonderful, full of lovely cards and ideas.
I've used Pool Party, Calypso Coral and a touch of Crushed Curry for the background. I've reduced the size of the three elements around the sentiment strip but retained the idea of having one tucked under the sentiment.
Card: Crumb Cake, Pool Party, Whisper White, watercolour paper
Stamps: Beachy Little Christmas
Inks: versamark, Crumb Cake
Other: white embossing powder, dimensionals.
All products Stampin' Up.